Container lid



Nov. 25, 1969 N. c. ELLIOT 3,480,177

CONTAINER LID Filed Dec. 22, 1967 INVENTOR. NEIL C. ELLIOT ATTORNE Y United States Patent 3,480,177 CONTAINER LID Neil C. Elliot, East Granby, Conn., assignor t0 Monsanto Company, St. Louis, Mo., a corporation of Delaware Filed Dec. 22, 1967, Ser. No. 692,809 Int. Cl. B65d 41/18, 21/02, 43/10 U.S. Cl. 220-97 7 Claims ABSTRACT OF THE DISCLOSURE A nestable, plastic container lid having stacking means which include male and female projections in the endwall and sidewall of the lid which cooperate with similar configurations in adjacently stacked lids to limit movement of the supported lid.

This application relates to a container lid, and more particularly to a nestable, plastic container lid.

Thermoplastic containers are becoming increasingly useful in packaging and storage applications of all types. These containers are usually closed with snap-on lids made of relatively thin plastic in order to minimize material costs and to facilitate a rapid production rate of the lids. The lids functionally must seal tightly, yet be easily removable by .a consumer, and resealable on the container body in cases where only portions of the contents are used on each opening of the container, The cost and production objectives have been achieved, and lids have even been manufactured which adequately serve their required function regarding the manner in which they close the container. However, it has been found that difliculties arise in processing such lids on high speed automated packaging equipment. More specifically, these lids are not adapted to be consistently individually and successfully fed from a stacked formation, as required in dispensing lids from a nested stack in a magazine, operating in conjunction with a capping machine. This deficiency has proven a great handicap in the practical usefulness of such container lids, and is basically due to the fact that the thin wall sides of the lids are so highly flexible that they readily warp and slide or snap over each other during handling and feeding operations. When this occurs segments of the rim portions of adjacently nested lids become interlocked, there-by preventing successive, smooth feeding of the lowermost stacked lid.

Attempts have been made to incorporate provisions in a lid of the type mentioned to overcome the jamming problem. In the past these involved forming inwardly extending peripheral wall portions having a slope opposite opposite to the general outward flare of the sides, so as to function as a shelf for supporting an adjacently stacked lid. However, these reversely angled peripherally extending shelves create molding problems since they tend to interfere with discharge of the lid from its mold cavity, thereby resulting in reduced production rates, and at times distortion of the lid.

The problem presented is not only to provide tight sealing, resealable lids which are free of objectionable wedging problems when nested together, but also to accomplish this in an economical manner so as not to counteract the low cost of producing lids.

It has now been found that this dilemma of difficulties which has only been compromised in the past has been effectively solved by the present invention. There is provided a stackable, snap-on, tight sealing, resealable plastic lid having positive means formed therein to insure trouble free denesting, which can be readily produced at high production rates.

Accordingly, it is an object of the present invention to provide :an improved stackable or nestable container lid which avoids the prior art difficulties discussed above.

3,480,177 Patented Nov. 25, 1969 It is another object of this invention to provide a nestable container lid adaptable for trouble free use in automated packaging operations.

It is a further object of this invention to provide a nestable container lid without using a troublesome reversely angled nesting shelf.

It is another object of this invention to provide a nestable lid modification for eliminating wedging together of stacked lids, yet is a configuration which may be used with existing automated packaging equipment without requiring major changes to accommodate it.

It is another object of this invention to provide a nestable container lid which is provided with positive means to limit radial movement of either an entire lid or of its sidewall when the lid is positioned in a stacked formation.

It is a further object of this invention to provide a thermoplastic lid which in addition to the above mentioned objects may be economically manufactured at a relatively low cost.

These and other objects will in part be obvious and will in part appear hereinafter.

These and other objects are accomplished by providing a nestable, plastic lid comprising an endwall, a sidewall integrally attached to and extending substantially perpendicular to the periphery of the endwall, stacking means associated with the endwall and the sidewall, and means for effecting attachment of the lid to a complementary portion of :a container body. The stacking means comprises an interlocking groove and a mating projection associated with the outer surface of the endwall and the base of the sidewall, which engage similar means in adjacent lids when :a plurality of lids are stacked together, in order to limit radial movement of the supported lid.

In describing the overall invention, reference will be made to preferred embodiments illustrated in the accompanying drawings in which:

FIG. I is a top plan view of a lid embodying the invention;

FIG. II is an enlaregd, partial, sectional view taken along the line II--II of FIG. I, showing the lid of FIG. I in closure sealing engagement on a container body;

FIG. III is a partial, sectional, elevational view of a nested stack of the lids of FIG. I;

FIGS. IV and V are partial, sectional, elevational views of alternate embodiments of the invention; and

FIG. VI is a plan view of a lid portion showing another alternate embodiment of the invention.

With reference to the drawings, wherein identical numerals refer to identical parts, there is shown in FIGS. I- III, a thin wall, plastic, one piece, resilient, nestable, circular lid, generally indicated as 10, for a complementary portion of a container body generally indicated as 12. Body 12 has upwardly extending sides which termimate in a radially extending beadlike upper rim 26 having an inwardly extending portion 28 at its outer end. Lid 10 comprises endwall 14 for covering the open upper end of body 12, and peripherally continuous sidewall 16 integrally attached to and extending substantially perpendicular to and downwardly from the periphery of endwall 12. Sidewall 16 has locking means 18 formed therein for releasably securing lid 10 to container body 12 as generally indicated in FIG. II.

As an important aspect of the present invention, lid 10 further comprises stacking means associated with endwall 14 and sidewall 16, comprising interlocking projection 20 extending downwardly from the outer end of the base 21 of sidewall 16 and annular, peripherally continuous groove 22 in the outer surface of endwall 14 of lid 10. Projection 20 of an upper supported lid is designed to fit within groove 22 of a similarly shaped adjacently nested lower supporting lid, to limit the extent of radial movement of sidewall 16 of the supported lid when a plurality of lids are nested together in the manner depicted in FIG. III. Endwall 14 may have a depressed central area 15 surrounded by a ring shaped raised portion 17. Downwardly extending projection 23 may be integrally formed in endwall 14 and positioned such that it sealingly contacts upper surface 24 of outwardly extending rounded rim 26 in the upper portion of container body 12.

To remove lid from body 12, the bottom end of the lid sidewall may be grasped between the forefinger and thumb and gently pushed or pulled upwardly to initially disengage lid 10 from rounded rim 26 of body 12 in the particular peripheral area chosen to be open. After this initial disengagement, the lid may be thereafter peripherally peeled off of the remainder of the upper portion of the body, the upward pressure exerted on the resilient plastic lid tending to force locking ring 18 in sidewall 16 outwardly beyond rim 26 of body 12. Obviously if it is desired to reapply lid 10 to body 12 to reseal the container, lid 10 may be initially placed across the open mouth of the container body and then pressed downon the outer surface of the lid endwall, or a projecting lift tab or eccentric flange portion which it is desired-t0 wardly with the result that projection 18 of the resilient lid will be forced outwardly, over and around the outer surface of rim 26 of body 12 until it sealingly snaps into place against the outer surface of the inwardly tapering outer end 28 of rim 26. When this occurs, projection 23 abuts against top surface 24 of rim 26 to provide a secondary seal between the contents within body 12 and that provided by the engagement of ring 18 and projection 28.

Lids 10 are stacked as illustrated in FIGS. III.-V. In FIG. III projection extending downwardly from the base 21 of sidewall 16 of upper supported lid 10a fits within groove 22 of lower supporting lid 1%. Groove 22 of lid 10:: correspondingly accepts projection 20 of a third lid positioned above lid 10a, so that the stacking means of any single lid cooperates with similar means in two other lids, i.e. those on both sides of it in the stack. Lateral, radial movement of upper lid 10a is governed by the extent to which the width in a radial direction of groove 22 exceeds the width in a similar direction of projection 22. Outward flexing of sidewall 16 of resilient lid 10a so as to cause undesirable telescoping movement of sidewall 16 down over the outer periphery of lower lid 10b is similarly prevented by the trapped engagement of the lower end of the sidewall of the upper lid in the groove in the upper surface of the endwall of the lower lid.

FIG. IV shows an embodiment of the invention wherein the male and female type interlocking members are reversed from that shown in FIGS. I-III, the projection being in the endwall of the lid and the peripheral groove in the base of the sidewall. FIG. V illustrates the mating projections in a substantially flat endwall 32, with the locking ring in the sidewall replaced by a peripheral groove 34 designed to sealably surround a projection in the end of the container body.

FIG. VI illustrates an embodiment wherein the novel stacking means of the invention are peripherally interrupted, i.e. the peripheral groove in the outer surface of the endwall is divided into a series of depressions 36 circumferentially and preferably equally spaced from each other around the periphery of the lid. Similarly provided (not shown) are a series of spaced axial extensions in the base of the sidewall adapted to fit within depressions 36 of an adjacently stacked lower supporting lid in the manner described previously. This interrupted stacking means embodiment as depicted in FIG. VI functions similarly to that described previously, i.e. to inhibit radial movement of a lid within a stack, and to limit lateral outward flexing of the sidewall of a lid within a stack. In addition, the interrupted configuration provides the additional advantage of preventing rotational movement of a circular lid within a stack. This feature may be important, for example, when the retailer has printed matter or a label have oriented in a particular location within the. stack.

The above description and particularly the drawings are set forth for purposes of illustration only and are not to be taken in a limited sense.

Nestability as used herein means the capacity of a lid to resist telescoping or wedging, i.e. an upper lid being partially forced down past a lower lid when the stack is loaded from above or dropped from heights of from about 4 to 6 feet.

The interlocking groove and projection of the stacking means of the present invention may be used with a plug type container lid which is of the type that when it is in place, it projects partially down into the inside 0f the upper end of the container body, and is sealed by a projection snapping into place in a groove in the opposite part. In such a case, the stacking means would be associated with the top of an upwardly extending lid sidewall and the bottom face of the lid base wall. For example, the projection could be at the top of the sidewall and the groove in the outer face of the bottom wall. With the flush type of lid seal as depicted in the drawings, the inner surface of the lid seats against the upper margin of the container body and attaches to the container body outside its rim. As illustrated, with this design the stacking means are associated with the base of the lid sidewall and the top surface of the lid endwall.

The means for attaching or locking the lid to the mouth of the container body may be any of a number of different configurations other than the inwardly extending locking ring in the lid which engages the outer surface of a rounded rim in the body. For example, a lip on the body which snaps into a cavity in the lid sidewall may be used, or a hermetic sealant used either with or without mating snap attachment means is likewise satisfactory.

The stacking means of the present invention broadly refers to either substantially peripherally continuous or interrupted interlocking male and female or tongue and groove mating connections in the end and sidewalls of a container lid which coact with similar configurations in an adjacently stacked lid to provide stack stability or security against lateral movement of a lid within the stack formation. The stacked lids need not all be of the exact same design, as long as the interlocking parts of the stacking means is common to each. As mentioned, and shown in the drawings, the parts are interchangeable, i.e. the projection may be in either the lid endwall or sidewall with the opposite configuration in the other part. The depressed groove portion is usually substantially similar but of reversed configuration from that of the projection. However the depressed portion does not have to reversely match the projection since it is obvious that other configurations may be designed which may accomplish the same purpose, i.e. interlocking engagement.

For optimum stacking the axial length of a projection should be at least of an inch. Whether more than one projection is required when the stacking means are interrupted will depend for the most part on the particular configuration of the container. The mating cavity preferably approaches the dimension of the projection with a clearance of about 0.005 inch on either side allowed for production molding variances.

Although the illustrated embodiments show a lid of generally circular shape, it is obvious that the lid may be of other various shapes, e.g. square, oval, rectangular, oblong, triangular and the like.

The lids of the present invention are generally of the injection molded variety.

The material from which the lid is formed may be any plastic capable of being molded in accordance with the previously mentioned design parameters. Thermoplastics generally have the advantages of being tough, difi'icult to break under ordinary circumstances, and have suflicient strength to be fabricated relatively thinly for economy purposes, since the lids contemplated herein are for use with containers of the throw away type which are meant to be nonreusable after consumption of the initial contents. The resulting lid is unitary in construction, has no seams and is of the thin wall variety having a generally uniform thickness between about 2 to 80 mils.

Useable thermoplastics are polymer based on styrene, vinyl halide, vinyl acetate, cellulose acetate or butyrate, ethyl cellulose, acrylic acid esters, metacrylic acid esters, acrylonitrile, isobutylene, fluoroolefins and chlorofluoroolefins, polyolefins such as for example polyethylene, or isotactic polypropylene, polyacrylates, polymethacrylates, polycarbonates, polyvinyl chloride, polyethylene terephthalates, as well as copolymers, interpolymers, graft polymers, and chlorinated and chlorosulfonated polymers of the monomers corresponding to the above mentioned polymeric products, and mixtures of the same.

The present invention is particularly usefully employed with relatively soft and flexible thermoplastics having a flexural modulus of less than about 100,000, such as low and intermediate density polyethylenes, These materials possess the advantages of being readily deformable so as to accommodate any production variations in the dimensions of the mouth of the container body, and also because of their pliability provide an unusually tight seal when used with a body made of a stiffer material such as acrylonitrile, butadiene, styrene polymer. However, because of their thin walls and high flexibility, lid sides made of these materials readily warp, bend outwardly and undesirably telescope when stacked and subjected to relatively slight top loadings. The present invention, however, provides positive means in the lid to prevent this from occurring.

In general, the present lid finds particular utility in automated and semi-automated packaging lines, and wherever storage space dictates that a plurality of lids in nested or stacked relation must be stored. The present configuration may be used with existing automated packaging lines without requiring major equipment modifications, and may be incorporated into existing lid configurations without requiring major container design changes. The assembled package which may be a food container comprising the lid and container body is tightly sealed, yet easily openable and resealable. The lids have improved structural stability, and may be readily dispensed With little or no difiiculty from the bottom of a stack. Lid manufacturing difficulties in the molding operation are eliminated, particularly with respect to withdrawal of the lid from the mold since reversely angled stacking shelves are not used. Consequently, high manufacturing rates may be maintained at very low costs.

It will be understood that many variations and modifications of the embodiments herein described will be obvious to those skilled in the art, and may be carried out without departing from the spirit and scope of the invention.

What is claimed is:

1. A nestable, plastic container lid comprising:

(a) an end wall;

(b) a thin, flexible side wall integrally attached to and extending substantially perpendicular to the periphery of the end wall, said side wall normally tending to bend outwardly with respect to the end wall when vertically loaded;

(c) stacking means in the end wall and the side Wall comprising a groove having a generally U-shaped cross section and an interlocking projection which cooperate with similar stacking means in adjacently stacked lids to hold the side wall substantially perpendicular to the end wall, this position of the side wall being equivalent to a vertically unloaded position of the side wall of said first mentioned lid; and

(d) means for effecting attachment of the lid to a corn plementary portion of a container body.

2. A one-piece, nestable, plastic lid comprising:

(a) a top wall;

(b) a thin, flexible side wall downwardly extending from the periphery of the top wall, said side wall normally tending to bend outwardly with respect to the top wall when vertically loaded;

(0) stacking means in the outer surface of the top wall and the base of the side wall comprising a groove having a generally U-shaped cross section and an interlocking projection which cooperate with similar stacking means in adjacently stacked lids to hold the side wall substantially perpendicular to the top wall, this position of the side wall being equivalent to a vertically unloaded position of the side wall of said first mentioned lid; and

((1) means in the side wall for attaching the lid to a complementary portion of a container body.

3. The lid of claim 3 wherein the stacking means comprises a substantially peripherally continuous groove having a U-shaped cross section in the outer surface of the top wall and a substantially peripherally continuous projection in the base of the side wall for fitting within the groove in the top wall of an adjacently nested lid.

4. The lid of claim 2 wherein the stacking means is peripherally interrupted.

5. A one-piece, nestable, thermoplastic lid adapted to be positioned adjacent an open, upper end of a container body comprising:

(a) an end wall for covering the open upper end of the container body;

(b) a thin, flexible peripherally continuous side wall extending downwardly from the periphery of the end wall, said side wall normally tending to bend outwardly with respect to the end wall are vertically loaded;

(c) locking means in the side all for releasably securing the lid to the container body; and

(d) substantially peripherally continuous stacking means comprising a groove having U-shaped cross section in the top of the end wall, and a projection in the base of the side wall adapted to fit within the groove in the end wall of a similar, adjacently nested lid, to hold the side wall substantially perpendicular to the end wall, this position of the side wall being equivalent to a vertically unloaded position of the side wall of the first mentioned lid.

6. The lid of claim 5 wherein the thermoplastic is low density polyethylene.

7. The lid of claim 5 wherein the locking means is a peripherally extending groove in the lid which cooperates with a complementary peripheral and radially extending projection in the upper end of the container body.

References Cited UNITED STATES PATENTS 2,556,547 6/1951 LeNoir 22097 X 3,269,588 8/1966 Ruekberg 22097 X 3,360,152 12/1967 Leers 22042 X 3,373,896 3/1968 Davis 22060 FOREIGN PATENTS 1,100,883 9/1955 France.

1,106,241 5/1961 Germany.

GEORGE E. LOWRANCE, Primary Examiner U.S. Cl. X.R. 22060; 229-43 2222 5 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent: No. 3,480, 177 Dated November 25, 1969 Invent Neil C. Elliot It is certified that error appears in the above-identified patent and that: said Letters Patent are hereby corrected as shown below:

"enlarged".

WIILIAM I. 'SGHUYLER, JR- Gomissioner of Patents Column 2, line 40, change enlaregd" to Claim 3, line 1, change "3" to "2".

Claim 5, line 9, change "are" to "when".

v Claim 5, line 11, change "all" to "wall".

SIGNED AND SEALED JUL 141970 (SEAL) Attest:

Mo Fletch, I!

Attesting Officer gauged 

